## Trigonometry 7th Edition

$\sqrt 2$
To find out exact value of $\sec 45^{\circ}$, considering special triangle- $45^{\circ} - 45^{\circ} - 90^{\circ}$ $\sec 45^{\circ}$ = $\frac{hypotenuse}{side - adjacent - 45^{\circ}}$ $\sec 45^{\circ}$ = $\frac{\sqrt 2}{1}$ = $\sqrt 2$